Particles in liquids

Solid-liquid Flow of liquids in pipelines/filters Settling of particles in liquid (e.g. rust and sludge)... 

There are a large number of processes in the chemical industries that handle a variety of suspensions of solid particles in liquids. The application of filtration techniques for the separation of these heterogeneous systems is sometimes very costly. If, however, the discrete phase of the suspension largely contains settleable particles, the separation can be effected by the operation of sedimentation. The process of sedimentation involves the removal of suspended solid particles from a liquid stream by gravitational settling. This unit operation is divided into thickening,... 

The retentivity relative to solid particles (e.g., spherical particles of polystyrene of definite size) is found from experiments determining the amount of these particles in the suspension to be filtered before and after the filter media. The retentivity K is determined as follows where g, g" =amounts of solid particles in liquid sample before and after the medium, respectively. 

The retention efficiency of membranes is dependent on particle size and concentration, pore size and length, porosity, and flow rate. Large particles that are smaller than the pore size have sufficient inertial mass to be captured by inertial impaction. In liquids the same mechanisms are at work. Increased velocity, however, diminishes the effects of inertial impaction and diffusion. With interception being the primary retention mechanism, conditions are more favorable for fractionating particles in liquid suspension. 

Zweiteriiig, T.N., 1958. Suspension of solid particles in liquids by agitators. Chemical Engineering Science, 8, 244. 

This represents a correction on Stokes Law and is significant for 3 micron and smaller particles in gases and 0.01 micron and smaller particles in liquids. Table 4-8 gives values of 1. ... 

When high concentrations of particles are to be settled, the surrounding particles interfere with individual particles. This is particularly important when settling high concentrations of solid particles in liquids. For such hindered settling, the viscosity and fluid density terms in Equation 8.6 can be modified to allow for this. The walls of the vessel can also interfere with settling4,9. 

How is a bubble created in acoustic cavitation There are three mechanisms in nucleation of a bubble in acoustic cavitation [14], One is the nucleation at the surface of solids such as a liquid container, motes or particles in liquid, if present. Nucleation takes place especially at crevices of motes, particles or a liquid container (Fig. 1.3). 

In the solid and liquid phases, molecules are very close to each other. This is because forces hold the molecules together in the solid and liquid states. We have already studied intramolecular bonds within molecules in the previous chapter. In this chapter, we will examine the forces of attraction between the particles in liquids and solids. 

C3, 12, J2, M3, S8). The amplitude of angular oscillations decreases as E increases, and a very long cylinder falls steadily to high Rey(I2, J2). If Re > 3500 (S8), motion also occurs in a horizontal plane. For relatively low y, the cylinder oscillates about a vertical axis (12, S8), while for dense particles in liquids or particles in gases the cylinder rotates continuously about a vertical axis (C3,12). A cylinder with E = 1 follows a trajectory inclined to the vertical, and tumbles in the direction of horizontal travel (12). For F < 1, the axis oscillates and rotates about a vertical line, so that the secondary motion resembles the final stages of motion of a coin spinning on a flat surface (12). 

Figure 11.4 shows the velocity-time curves from the full solution for weightless rigid spheroids (y = 0) and for density ratios typical of particles in liquids (y = 2.65) and gases (y = 10 ). Figure 11.5 shows the ratio of the value of t for which 14 = 0.5 to the corresponding value for a sphere. The effect of spheroid... 

Neglect of added mass and history simplifies calculation of unsteady motion considerably. However, for y characteristic of particles in liquids, this introduces substantial errors as illustrated by curve 4 in Fig. 11.7. The accuracy of the simplification improves as y and Re increase, but even for y as high as 10 trajectories calculated neglecting history and added mass substantially underpredict the duration of accelerated motion. Neglect of added mass causes the predicted trajectory to be in error from the start of the motion. Since it is the... 

Figure 11.15 shows predictions for density ratios typical of bubbles and of particles in liquids and gases. For low frequency (high To), the particle follows... 

Al-Taweel and Carley (A3) found that the amplitude ratio for particles in liquids is given by the creeping flow results in Table 11.2 at low frequency (tq > 0.2), while the ideal fluid result, Eq. (11-60) with A = 1, applies at high frequency (to < 0.002 to 0.01, dependent on y). 

Fig. 9.4.29 Comparison of stability of metallic nanoparticles in bulk liquid with a droplet on a metal surface, (a) Wetting of a droplet on a metal surface, (b) Coagulation and dispersion of metallic particles in liquid. Figures on the left-hand side stand for weak interaction in case A causing coagulation in case B. Those on the right-hand side are a strong interaction between metal and liquid, suggesting good dispersion and good contact.

Suspending of Solid Particles in Liquid in Stirred Tanks... 

Bubble columns in which gas is bubbled through suspensions of solid particles in liquids are known as slurry bubble columns . These are widely used as reactors for a variety of chemical reactions, and also as bioreactors with suspensions of microbial cells or particles of immobilized enzymes. 

---